Substituted 3-phenanthridinone derivatives as 5-alpha-reductase inhibitors

ABSTRACT

The present invention provides for the preparation of compounds,namely, 3-phenanthridinones and their derivatives and their unique ability to inhibit 5-alpha-reductase or their isozymes thereof in mammals enabling said compounds for treating hyperandrogenic conditions of acne, androgenic alopecia, male pattern baldness,female hirsutism,benign prostatic hyperplasia, prostatitis and prostatic cancer.

CROSS-REFERENCE

This application is a 371 of PCT/US94/03080 filed Mar. 22, 1994, whichis a continuation of Ser. No. 08/036,645 filed Mar. 24, 1993, (nowabandoned).

FIELD OF THE INVENTION

The present invention provides novel compounds, novel compositions,methods of their use and methods of their manufacture, where suchcompounds are generally pharmacologically useful as agents in therapieswhose mechanism of action rely on the selective inhibition of theisozyme 5α-reductase 1.

BACKGROUND OF THE INVENTION

Certain undesirable physiological manifestations, such as acne vulgaris,seborrhea, female hirsutism, male pattern baldness (alopecia) and benignprostatic hyperplasia, are the result of hyperandrogenic stimulationcaused by an excessive accumulation of testosterone or similarandrogenic hormones in the metabolic system. Early attempts to provide achemotherapeutic agent to counter the undesirable results ofhyperandrogenicity resulted in the discovery of several steroidalantiandrogens having undesirable hormonal activities of their own. Theestrogens, for example, not only counteract the effect of the androgensbut have a feminizing effect as well. Non-steroidal antiandrogens havealso been developed, for example,4'-nitro-3'-trifluoromethyl-isobutyranilide. See Neri, et al.,Endocrinol. 1972, 91 (2). However, these products, though devoid ofhormonal effects, compete with all natural androgens for receptor sites,and hence have a tendency to feminize a male host or the male ferns of afemale host and/or initiate feed-back effects which would causehyperstimulation of the testes.

The principal mediator of androgenic activity in some target organs,e.g. the prostate, is 5α-dihydrotestosterone, formed locally in thetarget organ by the action of testosterone-5α-reductase. Inhibitors oftestosterone-5α-reductase will serve to prevent or lessen symptoms ofhyperandrogenic stimulation in these organs. It is now known that asecond 5α-reductase isozyme exists, which interacts with epidermaltissues, especially in scalp tissues. This form is conventionallydesignated as 5α-reductase 1, while the isozyme that principallyinteracts with the prostatic tissues is designated as 5α-reductase 2.Both isozymes are active in the prostatic tissues. Thus, in thetreatment of hyperandrogenic disease conditions e.g. benign prostatichyperplasia (BPH), it would be desirable to have one drug entity whichis active against both isozymes in the prostate to significantly inhibitdihydrotesterone production, while also having another drug entity whichis highly selective for inhibiting the isozyme 5α-reductase 1 associatedwith the scalp, for use in treating conditions of the skin and scalp,e.g. acne and alopecia in males and hirsutism in females. Additionally,such a selective 5α-reductase 1 inhibitor could also be used incombination with finasteride (PROSCAR®), which is highly selective for5α-reductase 2, for combination therapy in the treatment of BPH.Therefore it is an object of this invention to provide compounds thathave sufficient activity in the inhibition of one or both 5α-reductaseisozymes. It is an additional object of this invention to providecompounds that are useful in the treatment and/or prevention of benignprostatic hyperplasia. It is an additional object of this invention toprovide compounds that are useful in the treatment of female hirsutism,male pattern baldness, acne, androgenetic alopecia, prostatic cancer,and insufficient plasma levels of high density lipoproteins. Thecompounds of the invention have utility in one or more of theaforementioned areas.

SUMMARY OF THE INVENTION

The compounds of the present invention are those of the generalstructural formula I: ##STR1## or a pharmaceutically acceptable salt orester thereof, wherein

R₁ and R₃ are independently selected from the group consisting ofhydrogen and C₁₋₆ alkyl;

R₂ is selected from the group consisting of hydrogen, C₁₋₆ alkyl, C₁₋₆alkoxyl and C₁₋₆ alkylcarbonyloxy;

X is selected from the group consisting of hydrogen, C₁₋₆ alkyl, C₁₋₆alkoxyl, C₁₋₆ alkoxy-C₁₋₆ alkyl, halogen, cyano, C₁₋₆ alkylcarbonyl,Ar-carbonyl, C₁₋₆ alkoxycarbonyl, C₁₋₆ alkylaminocarbonyl,Ar-aminocarbonyl and di-C₁₋₆ alkylaminocarbonyl; and

Ar is phenyl or pyridyl.

DETAILED DESCRIPTION OF THE INVENTION

Salts encompassed within the term "pharmaceutically acceptable salts"refer to non-toxic salts of the compounds of this invention which aregenerally prepared by reacting the free base with a suitable organic orinorganic acid. Representative salts include the following salts:

    ______________________________________                                        Acetate           Lactobionate                                                Benzenesulfonate  Laurate                                                     Benzoate          Malate                                                      Bicarbonate       Maleate                                                     Bisulfate         Mandelate                                                   Bitartrate        Mesylate                                                    Borate            Methylbromide                                               Bromide           Methylnitrate                                               Calcium Edetate   Methylsulfate                                               Camsylate         Mucate                                                      Carbonate         Napsylate                                                   Chloride          Nitrate                                                     Clavulariate      N-methylglucamine                                           Citrate           ammonium salt                                               Dihydrochloride   Oleate                                                      Edetate           Oxalate                                                     Edisylate         Pamoate (Embonate)                                          Estolate          Palmitate                                                   Esylate           Pantothenate                                                Fumarate          Phosphate/diphosphate                                       Gluceptate        Polygalacturonate                                           Gluconate         Salicylate                                                  Glutamate         Stearate                                                    Glycollylarsanilate                                                                             Sulfate                                                     Hexylresorcinate  Subacetate                                                  Hydrabamine       Succinate                                                   Hydrobromide      Tannate                                                     Hydrochloride     Tartrate                                                    Hydroxynaphthoate Teoclate                                                    Iodide            Tosylate                                                    Isothionate       Triethiodide                                                Lactate           Valerate                                                    ______________________________________                                    

The term "pharmacologically effective amount" shall mean that amount ofa drug or pharmaceutical agent that will elicit the biological ormedical response of a tissue, system, animal or human that is beingsought by a researcher or clinician.

The term "alkyl" shall mean straight or branched chain alkanes of one toten total carbon atoms, or any specified numbers within this range.

Whenever the term "alkyl" or its prefix root appears in a name of asubstituent (e.g. aralkoxyaryloxy) it shall be interpreted as includingthose limitations given above for "alkyl".

The compounds of the present invention can be administered in such oraldosage forms as tablets, capsules (each including timed release andsustained release formulations), pills, powders, granules, elixers,tinctures, suspensions, syrups and emulsions. Likewise, they may also beadministered in intravenous (both bolus and infusion), intraperitoneal,subcutaneous or intramuscular form, all using forms well known to thoseof ordinary skill in the pharmaceutical arts. An effective but non-toxicamount of the compound desired can be employed as an antiandrogenicagent.

The dosage regimen utilizing the compounds of the present invention isselected in accordance with a variety of factors including type,species, age, weight, sex and medical condition of the patient; theseverity of the condition to be treated; the route of administration;the renal and hepatic function of the patient; and the particularcompound or salt thereof employed. An ordinarily skilled physician orveterinarian can readily determine and prescribe the effective amount ofthe drug required to prevent, counter or arrest the progress of thecondition.

Oral dosages of the present invention, when used for the indicatedeffects, will range between about 0.05 to 1000 mg/day orally. Thecompositions are preferably provided in the form of scored tabletscontaining 0.5, 1.0, 2.5, 5.0, 10.0, 15.0, 25.0 and 50.0 mg of activeingredient. Effective plasma levels of the compounds of the presentinvention range from 0.002 mg to 50 mg per kg of body weight per day.Advantageously, compounds of the present invention may be administeredin a single daily dose, or the total daily dosage may be administered individed doses of two, three or four times daily. Furthermore, preferredcompounds for the present invention can be administered in intranasalform via topical use of suitable intranasal vehicles, or via transdermalroutes, using those forms of transdermal skin patches well known tothose of ordinary skill in that art. To be administered in the form of atransdermal delivery system, the dosage administration will, of course,be continuous rather than intermittant throughout the dosage regimen.Other preferred topical preparations include creams, ointments, lotions,aerosol sprays and gels, wherein the concentration of active ingredientwould range from 0.1% to 15%, w/w or w/v.

In the methods of the present invention, the compounds herein describedin detail can form the active ingredient, and are typically administeredin admixture with suitable pharmaceutical diluents, excipients orcarriers (collectively referred to herein as "carrier" materials)suitably selected with respect to the intended form of administration,that is, oral tablets, capsules, elixirs, syrups and the like, andconsistent with conventional pharmaceutical practices.

For instance, for oral administration in the form of a tablet orcapsule, the active drug component can be combined with an oral,non-toxic pharmaceutically acceptable inert carrier such as ethanol,glycerol, water and the like. Moreover, when desired or necessary,suitable binders, lubricants, disintegrating agents and coloring agentscan also be incorporated into the mixture. Suitable binders includestarch, gelatin, natural sugars such as glucose or beta-lactose, cornsweeteners, natural and synthetic gums such as acacia, tragacanth orsodium alginate, carboxymethylcellulose, polyethylene glycol, waxes andthe like. Lubricants used in these dosage forms include sodium oleate,sodium stearate, magnesium stearate, sodium benzoate, sodium acetate,sodium chloride and the like. Disintegrators include, withoutlimitation, starch, methyl cellulose, agar, bentonite, zanthan gum andthe like.

The compounds of the present invention can also be administered in theform of liposome delivery systems, such as small unilamellar vesicles,large unilamellar vesicles and multilamellar vesicles. Liposomes can beformed from a variety of phospholipids, containing cholesterol,stearylamine or phosphatidylcholines.

Compounds of the present invention may also be delivered by the use ofmonoclonal antibodies as individual carriers to which the compoundmolecules are coupled. The compounds of the present invention may alsobe coupled with soluble polymers as targetable drug carriers. Suchpolymers can include polyvinylpyrrolidone, pyran copolymer,polyhydroxypropyl-methacrylamide-phenol,polyhydroxyethylaspanamidephenol, or polyethyleneoxidepolylysinesubstituted with palmitoyl residues. Furthermore, the compounds of thepresent invention may be coupled to a class of biodegradable polymersuseful in achieving controlled release of a drug, for example,polylactic acid, polyepsilon caprolactone, polyhydroxy butyric acid,polyorthoesters, polyacetals, polydihydropyrans, polycyanoacrylates andcross-linked or amphipathic block copolymers of hydrogels.

The compounds of the present invention can be prepared readily accordingto the following reaction Schemes and Examples or modifications thereofusing readily available starting materials, reagents and conventionalsynthesis procedures. In these reactions, it is also possible to makeuse of variants which are themselves known to those of ordinary skill inthis art, but are not mentioned in greater detail. ##STR2##

The carbonyl of a phenanthrone such as 1 is protected as the ketal 2 byreaction with ethylene glycol in the presence of an acid with removal ofwater. The double bond which moves out of conjugation with theaforementioned carbonyl is oxidized to the ozonide which is subsequentlyoxidized with hydrogen peroxide. The resulting acid 3 is converted tothe acyl azide 5 via the acid chloride 4. Heating of 5 results in aCurtius rearrangement to the isocyanate which, along with the ketalprotecting group, is hydrolyzed in the presence of aqueous acid to thedione 6 which will spontaneously cyclize to the 3-phenanthridinone 7.Alkylation of the nitrogen with an alkyl iodide results in the formationof 8. ##STR3##

In Scheme II, Michael addition of N-alkyl homophthalimide tophenylthiomethyl vinyl ketone in the presence of base gives the adduct9. The side chain carbonyl is protected as the ketal and one of the ringcarbonyl groups is reduced with sodium borohydride and eliminated toform the isocarbostyril or isoquinolone-like compound 11. Subsequentketalization of the side chain carbonyl followed by reduction andcyclization yields the substituted 3-phenanthridinone 12. Oxidativeelimination of the phenylthio group gives the desired product 13.

The most preferred compounds of the invention are any or all of thosespecifically set forth in these examples. These compounds are not,however, to be construed as forming the only genus that is considered asthe invention, and any combination of the compounds or their moietiesmay itself form a genus. The following examples further illustratedetails for the preparation of the compounds of the present invention.Those skilled in the art will readily understand that known variationsof the conditions and processes of the following preparative procedurescan be used to prepare these compounds. All temperatures are degreesCelsius unless noted otherwise.

EXAMPLE 1 BIOLOGICAL ASSAYS

Preparation of Human prostatic and scalp 5α-reductases

Samples of human tissue were pulverized using a freezer mill andhomogenized in 40 mM potassium phosphate, pH 6.5, 5 mM magnesiumsulfate, 25 mM potassium chloride, 1 mM phenylmethylsulfonyl fluoride, 1mM dithiothreitol (DTT) containing 0.25 M sucrose using aPotter-Elvehjem homogenizer. A crude nuclear pellet was prepared bycentrifugation of the homogenate at 1,500 xg for 15 min. The crudenuclear pellet was washed two times and resuspended in two volumes ofbuffer. Glycerol was added to the resuspended pellet to a finalconcentration of 20%. The enzyme suspension was frozen in aliquots at-80° C. The prostatic and scalp reductases were stable for at least 4months when stored under these conditions.

5α-reductase assay

The reaction mixture contained in a final volume of 100 μl is: 40 mMbuffer (human scalp, potassium phosphate, pH 6.5; human prostatic5α-reductase, sodium citrate, pH 5.5), 0.3-10 μM¹⁴ C-T (or ³ H-T), 1 mMDTT, and 500 μM NADPH. Typically, the assay was initiated by theaddition of 50-100 μg prostatic homogenate or 75-200 μg scalp homogenateand incubated at 37° C. After 10-50 min the reaction was quenched byextraction with 250 μl of a mixture of 70% cyclohexane: 30% ethylacetate containing 10 μg each DHT and T. The aqueous and organic layerswere separated by centrifugation at 14,000 rpm in an Eppendorfmicrofuge. The organic layer was subjected to normal phase HPLC (10 cmWhatman partisil 5 silica column equilibrated in 1 ml/min 70%cyclohexane: 30% ethyl acetate; retention times DHT, 6.8-7.2 min;androstanediol, 7.6-8.0; T, 9.1-9.7 min). The HPLC system consisted of aWaters Model 680 Gradient System equipped with a Hitachi Model 655Aautosampler, Applied Biosystems Model 757 variable UV detector, and aRadiomatic Model A120 radioactivity analyzer. The conversion of T to DHTwas monitored using the radioactivity flow detector by mixing the HPLCeffluent with one volume of Flo Scint 1 (Radiomatic). Under theconditions described, the production of DHT was linear for at least 25min. The only steroids observed with the human prostate and scalppreparations were T, DHT and androstanediol.

EXAMPLE 2

A solution of 4a-methyl-4,4a,9,10-tetrahydro-2(3H)-phenanthrone 1 (7 g,33 mmol; prepared by the method of A. L. Campbell and J. D. McChesney,Syn. Commun. 1979, 9, 471-479) is dissolved in anhydrous benzene (300mL) and ethylene glycol (16 mL) and p-toluenesulfonic acid (0.7 g, 4mmol) added. The solution is refluxed with the removal of water in aDean-Stark trap according to the method of A. J. Vila, R. A. Spanevello,A. C. Olivieri, M. G. Sierra, and J. D. McChesney, Tet. Lett. 1989, 45,4951-4960 to form the ketal, 2-ethylenedioxy-4a-methyl-1,2,3,4,4a,9-hexahydrophenanthrene 2.

A solution of 2 is dissolved in methylene chloride and cooled to -78° C.and a stream of ozone is passed through it until a pale blue colorpersists. A solution of water containing 30% hydrogen peroxide is addedand the mixture warmed to 0° C. for 2 hr, then to room temperature for48 hr. Ethyl acetate is added and the solution successively washed with2% aqueous sodium bisulfite solution, water, and saturated saltsolution. The organic solution is dried over anhydrous sodium sulfateand the solvent removed by rotoevaporation to yield2-(4'-ethylenedioxy-1 '-methyl-2'-oxocyclohexyl)-phenylacetic acid 3.

The acid 3 is dissolved in diethyl ether and dimethylformamide andthionyl chloride is added. The solution is stirred at room temperaturefor 1 hr and poured into ice water. The ether layer is separated anddried over anhydrous sodium sulfate. The solvent is removed byrotoevaporation and the product,2-(4'-ethylenedioxy-1'-methyl-2'-oxocyclohexyl)-phenylacetyl chloride 4,is dissolved in acetone. Sodium azide is added and the solution stirredfor 20 min. Water is added and the mixture extracted with diethyl etherand the organic layer dried over anhydrous sodium sulfate. The solventis removed by rotoevaporation to yield2-(4'-ethylenedioxy-1'-methyl-2'-oxocyclohexyl)-phenylacetyl azide 5.

The acyl azide 5 is dissolved in dimethylformamide and heated to 100° C.until nitrogen evolution ceases. The solution is cooled and treated withaqueous acetic acid to form 2-(2', 4'-dioxo-1'-methyl-cyclohexyl)-benzylamine 6. Diethyl ether is added and the solution is washed successivelywith saturated sodium bicarbonate solution, water, and saturated saltsolution and dried over anhydrous sodium sulfate. The solvent is removedby rotoevaporation to yield 1,2,3,4,4a,5,6,10b-octahydro-10b-methyl-3-phenanthridinone 7.

A solution of 7 in dimethylformamide at 0° C. is treated with 1equivalent of sodium hydride followed by methyl iodide. After stirringat room temperature, diethyl ether is added and the solutionsuccessively washed with water and saturated salt solution. The solventis removed by rotoevaporation to yield1,2,3,4,4a,5,6,10b-octahydro-5,10b-dimethyl-3-phenanthridinone 8.

EXAMPLE 3

3(2H)-Phenanthridinone derivatives have been prepared fromhomophthalimide by the method of H. Iida et al., (Heterocycles 1983, 20,227-30). 2-Methyl-homophthalimide is reacted with phenylthiomethyl vinylketone (prepared by the method A. G. Schultz et al.,J. Am. Chem. Soc.1978, 100, 2140-9) in the presence of Triton B according to thedescribed method to form2-methyl-4-(3'-oxo-4'-phenylthiobutyl)-homophthalimide 9.

Reaction of 9 with ethylene glycol and p-toluenesulfonic acid inrefluxing anhydrous benzene with removal of water by a Dean-Stark trapgives 4-(3'-ethylenedioxy-4'-phenylthiobutyl)-2-methylhomophthalimide 10which is reduced with sodium borohydride and treated with aqueoushydrochloric acid to form2-methyl-4-(3'-oxo-4'-phenylthiobutyl)-isocarbostyril 11.

Ketalization of 11 with ethylene glycol in the presence ofp-toluenesulfonic in reluxing benzene follows as above. Reaction of theketal with lithium aluminum hydride in diethyl ether followed bytreatment with concentrated hydrochloric acid at 100° C. gives5-methyl-1,2,3,4,4a,5,6,10b-octahydro-4-phenylthio-3-phenanthridinone12. Treatment of 12 with basic hydrogen peroxide gave5-methyl-1,2,3,4,4a, 10b-hexahydro-3-phenanthridinone 13.

While the invention has been described and illustrated with reference tocertain preferred embodiments thereof, those skilled in the art willappreciate that various changes, modifications and substitutions can bemade therein without departing from the spirit and scope of theinvention. For example, effective dosages other than the preferreddosages as set forth herein above may be applicable as a consequence ofvariations in the responsiveness of the mammal being treated for any ofthe indications for the compounds of the invention indicated above.Likewise, the specific pharmacological responses observed may varyaccording to and depending upon the particular active compound selectedor whether there are present pharmaceutical carriers, as well as thetype of formulation and mode of administration employed, and suchexpected variations or differences in the results are contemplated inaccordance with the objects and practices of the present invention. Itis intended, therefore, that the invention be limited only by the scopeof the claims which follow and that such claims Be interpreted asbroadly as is reasonable.

What is claimed is:
 1. A compound of the formula I ##STR4## or apharmaceutically acceptable salt or ester thereof, whereinR₁ and R₃ areindependently selected from the group consisting of hydrogen and C₁₋₆alkyl; R₂ is selected from the group consisting of hydrogen, C₁₋₆ alkyl,C₁₋₆ alkoxyl and C₁₋₆ alkylcarbonyloxy; X is selected from the groupconsisting of hydrogen, C₁₋₆ alkyl, C₁₋₆ alkoxyl, C₁₋₆ alkoxy-C₁₋₆alkyl, halogen, cyano, C₁₋₆ alkylcarbonyl, Ar-carbonyl, C₁₋₆alkoxycarbonyl, C₁₋₆ alkylaminocarbonyl, Ar-aminocarbonyl and di-C₁₋₆alkylaminocarbonyl; and Ar is phenyl or pyridyl.